Sunlight Calculator
Check window daylight by date
📱 Phone: auto-measure with sensor · 💻 PC: pick the direction manually
How to use (phone)
① Hold your phone level at the window (green level)
② Point the top of the phone toward the outside direction the window faces
③ Pick a date to see that day's sunlight
🔒 Location is used only on your device and never stored.
How to use (phone)
① Hold your phone level at the window (green level)
② Point the top of the phone toward the outside direction the window faces
③ Pick a date to see that day's sunlight
🔒 Location is used only on your device and never stored.
☀️ Light Intensity Terms
Direct light: sun hits nearly head-on, strongest (incidence 0-30°)
Angled light: enters at an angle, moderate (30-60°)
Weak angled: low to the side, weak (60-85°)
No light: behind the window or below horizon
Window Direction
FAQ
Can I preview other dates?
Yes. Pick a date or use the spring/summer/autumn/winter quick buttons to recalculate for that date. You can compare how sunlight differs between summer and winter for the same window.
Why does it differ by season?
The sun's height changes with the season. In winter the sun is low, casting deep and long light into south windows; in summer it's high, giving short shallow light. Useful to gauge winter daylight before moving.
Can I use it on a PC?
Yes. On a PC there's no orientation sensor, so just choose the window direction (south, east, etc.). You can compare seasons by changing the date. On phones it's measured automatically.
What does tapping a bar show?
The sun's azimuth, altitude, and light level at that time, so you can see exactly where the sun is.
Can results differ from reality?
Yes. These are theoretical values based on sun position only; buildings, trees, awnings, and window size are not included. Use as a reference.
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